Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 221053 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 553 AM EST Mon Jan 22 2018 .SYNOPSIS... Some light precipitation is expected today and tonight. Most of it will be rain, but light icing is likely over interior high terrain especially tonight into early Tuesday. A fast moving storm system will bring a period of heavy rain to the region Tuesday along with strong winds across SE New England. Blustery, dry and colder weather follows Wednesday through Friday, then a warming trend next weekend. A cold front may bring showers by next Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A warm front is slowly pushing NE as it weakens early this morning. This, along with cold high pressure across Quebec at 09Z has kept low level cold air to remain across central and northern areas. This has produced spotty light rain along with pockets of freezing rain and sleet. However, where the steadier precip has fallen, it has dragged some of the milder air aloft down to the surface, allowing temps to rise to at or above freezing across the central and southern CT valley eastward into E Mass, though still noting some temps hovering around freezing even on Cape Cod with calm winds. Continue to see a zonal flow aloft as cutoff H5 low pressure sits across the central plains states early this morning. As the large Canadian high shifts E today, surface low pressure will lift to the Great Lakes. The cyclonic circulation around this deepening low will bring winds around to S-SE during the day. Will still see some overrunning precip work in across the region, but temps will continue to slowly rise during the day with any leftover mixed precip to change over to rain by mid morning. Will see light rainfall today, with around 0.1 inches or so of precip to fall. Expect highs to only reach the mid and upper 30s across central and N Mass, ranging to the lower 40s further S. The big question will be whether more freezing precip will develop during this afternoon across N central and W Mass as the front remains stationary close to those locations. At this point, it does look like there will be some light freezing rain developing again during the afternoon and into the evening as winds back to E-SE by evening. A Winter Weather Advisory has been issued from this afternoon through tonight. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Tonight... A stalled front near or just N of the region will not move much tonight as the low moves into the western Great Lakes. With the colder air sitting across northern New England, noting the cold air damming signature becoming better established tonight, especially across N central and NW Mass. The bulk of the precip will shift into northern New England, but will still see more spotty light precip linger across the region. With the cold air in place, and milder air working in aloft, will see periods of light freezing rain continue. As mentioned above, the Winter Weather Advisory remains in effect from N Worcester county westward through the night. May see up to 0.1" ice accretion across portions of the Route 2 corridor mainly W of the Merrimack Valley, where the best chance for freezing rain will occur. The warm front S of the region will start to lift N overnight, so will see temps rise after midnight mainly toward daybreak along the S coast, with readings holding around freezing well inland. Tuesday... As the low pressure across the Great Lakes lifts into southern Ontario, will see another shot of milder air lift northward. This is also associated with a very strong low level jet, on the order of 50-55 kt, which will move across portions of RI/SE Mass during the morning and midday hours. Noting very good low level mixing in place, along with an increasing pressure gradient as the low to the W strengthens. Could see S winds gusting up to 35-45 mph Tuesday morning into midday as the jet passes. Also noting a deep tropical moisture connection, as PWAT plume of 1 to 1.25" works across the region. Will also see some good instability ahead of the approaching cold front as total totals rise to the lower 50s. Have also mentioned the chance for an isolated thunderstorms as the front crosses the region from midday through the afternoon hours. An area of moderate to heavy rainfall will cross the region during the day, with the highest amounts (up to around 1 to 1.3 inches across N central and W Mass) moving across. There is a risk for some urban and poor drainage flooding in any heavy downpours. Could also see some issues along some of the mainstem rivers, especially along the Connecticut River where the higher precipitation is expected to fall. Have held off issuing a Flood Watch at this point, but will continue to monitor this aspect closely. Will see temps reach to lower-mid 50s across central and southern areas, but remain in the upper 40s across the higher terrain. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Highlights... * Blustery and colder Wed, and especially Thu/Fri, but dry * Much milder next weekend with showers possible by Sunday Tuesday night... Cold front will be in the vicinity of the Cape/Islands Tue evening then moving offshore. Some lingering showers are possible here early, and a few rain to snow showers possible western MA in the evening as mid level trough swings through. Otherwise, gradual clearing will develop although some lower clouds may linger across NW MA. Gusty west winds will develop overnight as low level cold advection increases. Wednesday through Friday... Blustery and colder pattern as longwave trough develops over the NE but mainly dry weather expected with dry column and subsidence. Near normal temps Wed, then trending below normal Thu/Fri. Core of the coldest air aloft on Thu with 850 mb temps near -15C. This will result in highs Thu mainly in the 20s to near 30 with gusty winds making it feel considerably colder, while Thu night wind chills drop into the single numbers and subzero higher terrain. Temps recover Fri as heights begin to rise and low level temps moderate but a cold start will hold temps from the upper 20s to mid 30s. Saturday and Sunday... Return to milder airmass and well above normal temps as high pres moves offshore and mid level ridge builds north along the east coast. 850 mb temp anomalies 1-2SD and EPS/GEFS ensembles have fairly high probs of 50s in the coastal plain by Sun. Deterministic GFS looks too fast with next approaching trough and not supported by majority of GEFS members so we leaned toward slower ECWMF solution given downstream ridging in place over the western Atlantic. Next chance of showers assocd with the mid level trough and attending cold front should hold off until Sunday or possibly Sat night. Very low risk of some icing distant interior if precip comes in Sat night but any freezing precip would probably be localized and this is a very low probability. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/... Through 12Z...Moderate confidence. CIGS lowering to MVFR-IFR by 12Z across central and western areas. Noting spotty light mix of -RA/-SN/-FZRA mainly across the E slopes of the Berkshires to N Worcester county and the Merrimack valley through daybreak. Today...Moderate confidence. Mainly IFR CIGS/MVFR-IFR VSBYS. Increasing chance of -RA through the day, with chance for -FZRA developing across N central and NW Mass by late afternoon. Light winds shift to E-SE by evening. Tonight...Low to Moderate confidence. MVFR-IFR CIGS for most areas. Rain most places with -FZRA across N central and NW Mass as winds shift to E- there. Across S areas, winds shift to S and increase after midnight, with CIGS lifting to VFR but MVFR-IFR VSBYS linger in patchy fog. Tuesday...Moderate confidence. Mix of conditions from locally VFR to start across N CT/RI/SE Mass, ranging to IFR across N central and W Mass. Conditions lower to MVFR-IFR as cold front approaches, bringing low clouds and areas of locally heavy rain. Low chance of TSRA. Depending upon the timing of the cold front, conditions may improve to VFR across western areas during the afternoon. KBOS Terminal...Moderate to high confidence in TAF. KBDL Terminal...Moderate to high confidence in TAF. Outlook /Tuesday Night through Friday/... Tuesday Night: Mainly VFR, with local MVFR/IFR possible in the evening across Cape/Islands. Windy with gusts to 30 kt. Slight chance SHRA in the evening. Wednesday: VFR. Windy with gusts to 30 kt. Wednesday Night through Friday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...Moderate confidence. Today... Light E-SE winds increase to around 10 kt during the day. Seas build up to 2-3 ft. Visibility reduced to around 3 miles during the afternoon in rain and fog. Tonight... Wind shift to SE-S during the night, with gusts increasing to 20-25 kt. Seas build to 3-5 ft on the outer waters after midnight. Visibility lowering to 1-3 miles in rain and fog. Tuesday... Gale warning issued for all waters. S winds increase, gusting up to 35-40 kt, highest from mid morning through the afternoon. Seas build up to 6-9 ft. Visibility 1-3 miles in rain and fog. Chance for isolated thunderstorm. Outlook /Tuesday Night through Friday/... Tuesday Night: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 12 ft. Slight chance of rain showers. Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 11 ft. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Thursday through Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Friday: Winds less than 25 kt. Local rough seas. && .HYDROLOGY... A Flood Warning remains in effect for the Connecticut River at Middle Haddam, where ice jams are causing river fluctuations. No significant change from earlier forecasts. For details on specific area rivers, including observed and forecast river stages, please visit the Advanced Hydrologic Prediction Service (AHPS) graphs on our website. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Weather Advisory from 3 PM this afternoon to 9 AM EST Tuesday for MAZ002>004-008-026. RI...None. MARINE...Gale Warning from 9 AM to 8 PM EST Tuesday for ANZ232>235-237- 250-254>256. Gale Warning from 10 AM to 6 PM EST Tuesday for ANZ230-231-236- 251. && $$ SYNOPSIS...KJC NEAR TERM...EVT SHORT TERM...EVT LONG TERM...KJC AVIATION...WTB/KJC/EVT MARINE...WTB/KJC/EVT HYDROLOGY... is the U.S. government's official web portal to all federal, state and local government web resources and services.